Critical Speed Analysis of Aero-Engine Considering Rotor Casing Coupling Effect
The research on critical speed is an important part of aero-engine design.At present,in order to achieve high perfor-mance,the requirement for reducing the important case of aero-engine is constantly increasing.As a result,most of the aero-en-gines adopt thin-wall structure,which leads to the obvious enhancement of coupling effect between the case and the rotor.There-fore,based on the structural characteristics of twin-rotor aero-engine,this study establishes the mechanical model of engine cou-pling,and theoretically analyses the coupling mechanism of rotor system and casing and its influence on critical speed.In order to verify the influence of rotor-casing coupling on critical speed,a single rotor dynamic model without rotor-casing coupling and a complete machine model with coupling are used to solve the critical speed of high-pressure and low-pressure rotors respectively.By comparing and analyzing the results,it is found that there are large errors in the critical speed results obtained by the two models.The critical speed order of the high-pressure rotor required by the two models is different,and the second-order critical speed error required by the low-pressure rotor is 62.7％,which is unacceptable.Therefore,it is more reasonable to solve the critical speed of the aero-engine by using the whole-machine coupling model considering the coupling effect between the rotor and the casing.
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